Vertex Groups assignment from Makehuman mesh
Selection

You could assign the vertex groups (VGs) starting from a hand make sure that you name the groups with suffixes e.g ForeArm.L, ForeArm.R (this is required to let Blender know which vertex groups correspond).



Invert the selection Ctrl-I 


Deselect (MMB while in Select Mode) all vertices which should not belong to the ForeArm VG. Note that you can also use already assigned VGs to help exact deselecting (especially for the head and upper body parts).

Repeat this process for all VG assignments on one side.



Mirroring (using Mirror Modifier)

Finally use Mirror Vertex Group to copy the VG data from one side to the other, Note that empty VGs with matching names are required.



The mirror isn't very intuitive due to its prerequisites, therefore I suggest first to watch the video and first try it with a single VG:

Video Mirror Vertex Groups (Spanish)

From the docs of Mirror Modifier


  Vertex Groups 
  When this button is enabled, the Mirror modifier will
  try to mirror existing vertex groups. A very nice feature, but that
  has quite specific prerequisites. First, the vertex groups you want to
  mirror must be named following the usual left/right pattern (i.e.
  suffixed by something like “.R”, “.right”, “.L”, et cetera). Next, you
  must have the “mirrored” groups already existing (i.e. same names
  suffixed by the “other side”) and completely empty (no vertex assigned
  to it), else it won’t work. Usually, the mirrored copies of the
  vertices of a group remain in this group. Once this option is
  activated, all groups following the rules described above will only be
  valid on the original object – the mirrored copy will put these same
  vertices into the “mirror” group. Very handy with armatures, for
  example: you just model half of your object, carefully rig it with
  half of your armature, and just let the Mirror modifier build the
  other half. Just be sure to put your Armature modifier(s) after the
  Mirror one. A final word about multi-axes mirror: in these cases, the
  “direct”, “first level” copies get the mirrored groups, the copies of
  copies (“second level”) get the original groups, et cetera.